Covered railroad hopper cars typically include a walled enclosure mounted on an underframe of the car. As is conventional, the underframe of the car is supported toward opposite ends thereof by the usual wheeled trucks which ride on tracks or rails. A bottom of the walled enclosure is usually provided with a series, typically one or more, individual discharge openings for allowing the particulate matter held and transported within the enclosure to be discharged therefrom. The walled enclosure furthermore usually includes sloped or slanted walls or sheets extending upwardly from the periphery of each discharge opening to promote gravitational movements of the particulate matter toward the openings.
Various methods and devices are known in the art for individually closing the plurality of discharge openings in the walled enclosure of the hopper car. A slide gate mechanism is typically used in combination with each individual discharge opening on the hopper car. A conventional slide gate mechanism or device includes a frame which is bolted or otherwise connected to the walled enclosure on the hopper car. The frame defines an opening which, when the gate is assembled to the hopper car, is in registry with the discharge opening on the hopper car thereby permitting particulate matter to pass therethrough. A gate is arranged on the frame for sliding movement between open and closed positions relative to the discharge opening. When open, the gate permits the contents of the hopper car to gravitationally pass from the car. When closed, the sliding gate shuts off the matter or material flow through the gate. Typically, the gate is slidably driven between positions through an operating shaft assembly rotatably mounted on the frame and including a conventional rack and pinion. As will be appreciated by those skilled in the art, opposite ends of the operating shaft assembly are engagable by a power driven tool to drive the gate between positions.
Existing unloading sites usually have two parallel and adjacent unloading pits that are about 36 to 40 feet in length and a yard having a capacity for storing in excess of 500 railroad hopper cars. The unloading area is typically sheltered from rain and snow and the railroad cars are spotted over the unloading pits by using two car pullers (one for each track). Locomotives are used to move the hopper cars into range of the spotters and the railroad hopper cars are usually stationary during the unloading process. When the slide gate mechanisms are opened, an operator is required to use one of three portable power drivers or tools to independently operate the sliding gate associated with each discharge opening on the railroad car. Preferably, the discharge of material from the hopper car is limited to between the tracks since any material dropped on the rails has the potential for causing a derailment and the discharged material will be contaminated.
Unloading of the railroad hopper cars involves three to four persons located between the two unloading pits. This arrangement allows access to both tracks from one location using three power driven tools. As will be appreciated by those skilled in the art, each power tool has a free end configured to interface with either end of the operating shaft assembly on the slidable gate. Each tool is configured to handle a specific style of gate or gate operating handle. It has also been found it takes approximately five to seven minutes to empty a standard size hopper car.
During unloading, a hatch on a top of the covered hopper car should be opened to equalize the pressure within the walled enclosure as the particulate matter or ballast passes therefrom. Although inconvenient, failure to open a hatch on the top of the hopper car can result in the car imploding during the unloading process.
As will be appreciated, unloading of covered hopper cars involves a manually intensive effort. Moreover, time is of the essence. In view of future demands, unloading sites are preparing for quicker and easier ways to unload the hopper cars and convey the particulate matter or ballast away from the unloading pits. Some sites are preparing their unloading procedures such that the hopper cars can be unloaded while on the move rather than remaining stationary.
Thus, there is a need and a desire for a door assembly for hopper cars which allows the particulate matter stored and transported within the walled enclosure of the hopper car to be discharged rapidly from the hopper cars and between the rails with minimum operator intervention.